The need for vaccines to control malaria and other parasitic diseases remains unabated. For malaria, the need is particularly pressing as it continues to dominate vast subtropical and tropical areas of the world. An effective vaccine against this disease would contribute significantly to restraining it and dulling the sharp cutting edge of its repeated resurgence.
For lack of effective immunization procedures, malaria and other parasitic diseases continue for the most part to be treated after inception, with varying degrees of success. While numerous attempts have been made to isolate protective antigenic factors associated with these parasites, purification and recovery of antigens having a high immunizing efficiency in quantities suitable for large scale administration have not been effected for most infectious parasitic diseases.
Rodents and primates have been variously vaccinated against malaria with crude plasmodial fragments separated from host blood cells {see e.g., D'Antonio, et al., Nature 223: 507-509 (1969) (Reference I); D'Antonio, et al., Science 168: 1117-1118 (1970) (Reference II); D'Antonio, et al., Exptl. Parasitology 31: 75-81 (1972) (Reference III)}, isolated membrane particles {see e.g., References II; III; D'Antonio, et al., J. Am. Osteopathic Assoc. 73: 649-652 (1974) (Reference IV); Speer, et al., J. Protozool. 23: 437-442 (1976) (Reference V)}, and most recently, purified membrane subfractions {see e.g., D'Antonio, et al. in Immunological and Serological Aspects of Clinical Parasitology, W. Ball and V. Iralou, Eds. (Eastern Penn. Branch of the Am. Soc. for Microbiology, P. 59, 1981) (Reference VI}. However, further purification of the involved protective antigen(s) has been hampered by the absence of effective non-denaturing techniques for separating them from their insoluble carrier components. For example, specific attempts to isolate malarial plasmodial protective antigens from associated plasmodial material with acetic acid (D'Antonio, et al., Abs. of the Am. Soc. for Microbiol., Abstr. E68, 1980) or lithium 3,5-diiodosalicylate (Reference VI and D'Antonio, et al., Abs. of the Am. Soc. for Microbiol., Abstr. E98, 1979) have not proved entirely successful. Thus, solubilization and recovery of such antigenic factors from these and related materials would open the way for their final purification and is the next crucial step in advancing the immunochemistry, immunobiology, and vaccine technology of malaria and related diseases.